Cross-linked polymers formed from bi- and trifunctional monomers create three-dimensional networks. Such crosslinking imparts which dominant class of properties to the material?

Introduction / Context:
When monomers with functionality greater than two react, they form crosslinked networks. This network architecture defines the thermoset class and controls heat response, solvent resistance, and mechanical behaviour.

Given Data / Assumptions:

• Bi- and trifunctional monomers can create infinite networks at gelation.
• Network polymers do not melt upon reheating.
• Elastomeric behaviour usually requires low crosslink density and soft segments, not the general case for highly crosslinked networks.

Concept / Approach:
Crosslinks produce thermosetting behaviour: dimensional stability at elevated temperatures, insolubility (though swelling may occur), and inability to be remelted. While networks can be brittle or toughened depending on formulation, the defining feature is thermosetting, not thermoplasticity.

Step-by-Step Solution:
Link network structure to processing behaviour.Exclude thermoplastic/ductile claims inconsistent with crosslinks.Select “Thermosetting.”

Verification / Alternative check:
Phenolics, epoxies, and melamine resins are crosslinked examples exhibiting thermoset behaviour.

Why Other Options Are Wrong:
Thermoplastic: melts and reforms, unlike networks.Unlimited elastomeric extensibility: not typical of highly crosslinked systems.Brittleness only: oversimplification; toughness can be engineered.Perfect ductility: inconsistent with crosslink constraints.

Common Pitfalls:
Assuming “crosslinked” always means extremely brittle; formulation strongly influences toughness.

Final Answer:
Thermosetting